Downdraft-furnace.



No. 633,27l. Patented Sept. I9, I899. 0. D. ORVIS.

DOWNDRAFT FURNACE.

(Application filed Oct. 31, 1898. 7 (No Model.) 5 Sheets-Sheet 1.

H ll

Win #1 74% 67 46 5 3 as J N0. 633,27|. Patented Sept. l9,l899.

- 0. D. ORVIS.

DOWNDRAFT FURNACE.

(Application filed Oct. 81, 1898.1

5 Sheets8hoet 2 (No Model.)

1%??7071 o 7" OreZ 0/7/65 No. 633,271" Patented Sept. l9, l899.

' 0. n. ORVIS.

DOWN DRAFT FURNACE.

[Applicatiun filed Oct. 31, 1898.)

5 Sheets-Sheet 5.

(No Model.)

MQ'mes 5 66 I I 711/671, 60 1" I? 00 02 652 OTVO'S Jay ' UNITED STATESPATENT OFFICE.

OREL D. ORVIS, OF CHICAGO,ILLINOIS.

DOWNDRAFT-FURNACE.

SPECIFICATION forming part of Letters Patent No. 633,271, datedSeptember 19, 1899.

Application filed October 31, 1898.

To all whom it may concern:

Be it known that I, OREL D. ORVIS, a citizen of the United States ofAmerica, and a resident of Chicago, county of Cook,and State ofIllinois, have invented certain new and usefullmproveinents inDowndraft-Furnaces, of which the following is a specification, and whichare fully illustrated in the accompan ying drawings, forming a partthereof.

This invention relates to that class of furnaces in which there areemployed both the downdraft and the updraft, the upper set of grate-barsbeing water-tubes and being connected with the boiler by means ofsuitable tubes, whereby a circulating system is pro vided, and the lowerset of grate-bars being adapted especially to receive the droppings ofunconsumed fuel from the upper set of grates.

The objects of the invention are to provide for the independentexpansion and contraction of the water-tube bars, to provide improvedmeans for burning the fuel upon the lower set of grates, to provide forthe burning of the smoke, and in accomplishin these various objectstoprovide increased efficiency in the generation of steam.

A further object is to secure an improved construction, generally andspecifically, of furnaces of this type and to adapt such a furnace toplants already installed.

These objects are attained by the various parts and arrangement of partshereinafter fully described and which are illustrated in theaccompanying drawings,.in which- Figure l is a front elevation of thefurnace and boiler, a portion being broken away to show the internalconstruction. Fig. 2 is a transverse vertical section inside of the rearwall of the furnace, looking forward. Fig. 3 is a longitudinal verticalsection on the line 3 3 of Fig. 1. Fig. 4 is a detail plan on the brokenline 4 l of Fig. 3. Figs. 5 and 6 are detail sectional views on thelines 5 5 and 6 6, respectively, of Fig. 4. Fig. 7 is a detail sectionon the line 7 7 of Fig. 2, and Fig. 8 is a detail plan section on theline 8 S of Fig. 2.

The face of the furnace is shown at A, its side walls at A A, its. rearwall at A the boiler at B, and a plate for closing the space between therear end of the boiler and the rear wall of the furnace at A Any desiredform of boilermay be employed. Ishow the $erial No. 695,039. (No model.)

ordinary tubular-flue boiler, and it may be A transverse partition adivides the furnacespace below the boiler, generally speaking, into afront and rear compartment, this partition extending entirely to thecrownsheet of the boiler and from side wall to side wall, flue-aperturesbeing provided through it, as hereinafter described.

The'circulating system com prises a waterleg 0, connected with theboiler B through its rearward end and communicating with a horizontalpipe 0, which leads to the front of the furnace and is connected bymeans of a short vertical pipe-section c with a header D, which, asshown, is'in front of the face of the furnace. The water-tube grate-barsE are connected with the header D, pass through the rearward end of theboiler B, and from which there extends a horizontal pipe F,which ispreferably continued, after entering the boiler, nearly to the frontthereof, so that whilethe water leaves the boiler at its rearward end itis returned to its forward end, thereby permitting the circulation notonly through the pipe system, but also through the boiler itself, whilestill admitting of the location of both connections with the boiler atits rearward end, avoiding the necessity of making connections with itscurved walls. Plugs may be provided, as shown, at any of the angles ofthe pipe system and in the headers opposite the ends of the pipesconnected thereto, and for the purpose of gaining access to the rearwardend of the pipe 0 it may be extended backwardly through the rear wall Aas shown at c.

The water-tubes E are preferably connected with the headers D d by thewell -known means of expanding, and I prefer to make them of lightmetal, so that the heatis readily transmitted therethrough, to theadvantage not only of the steam-generating qualities of the furnace, butof the tubes themselves, in that they are much less liable to burn outthan when thick tubing is used. By bending the tubes E, as shown, Iavoid the necessity of resorting to the expedient practiced by some ofproviding a telescopic connection with one of the headers in order toprovide for expansion and contraction. The heat is not uniformly appliedto these tubular gratebars. Usually a stronger fire is maintained nearthe central portion of the grated surface than at its margins, and,furthermore, some of the fuel may burn more sharply than other portions.As a result of these conditions some of the grate-bars have a greaterrange of expansion and contraction than others, and it therefore becomesnecessary to provide for the variations in the lengths of these pipesindependently of each other. The bent form of pipe shown accomplishesthis object, as the expansion of the tube slightly increases theflexure,whileits contraction tends to straight en it, and hence eachshould adjust itself independently of all the others and without unduestrain upon the headers. This vertical movement of the water-tubes, dueto their fiexure, is provided for by setting the masonry of the walls asomewhat open, as shown, the bricks, however, staying the tubeslaterally.

A further advantage in employing the bent form of tubular grate-bar isfound in the fact that the grated surface may be given a more decidedpitch or inclination from the horizontal than when straight tubes areused which enter a header at the rearward end of the fire-box, and as aresult the direction of draft through the grate is less objectionablethan when it is directed downward, and, furthermore, the vaporsdistilled are not obliged to hug the lower face of the grate as theypass backwardly, thereby choking the draft at the rearward part of thefire-box.

A still further advantage in the use of the bent water-tubes asdistinguished from the straight tubes entering a header at the rearwardend of the fire-box arises from the fact that the flue-openings in thewall a may be brought well up to the grate, so that it is not necessaryfor the vapors to be carried down any considerable distance to gain anentrance to these fines.

The lower grate consists of two sets of solid bars II h, arranged theone slightly above the other and set staggeredthat is to say, the barsof the one set alternating with the bars of the other set. I am awarethat the staggered arrangement of grate-bars has been employed in theupper-grates of a downdraftfurnacc, but when so employed give rise to aserious disadvantage in that the fuel has a tendency to choke up theair-passages, and hence must be freely dislodged by the use of aslice-bar. By the staggered arrangement of the lower set of grate-bars,on the contrary, a decided advantage is gained. Usually little or no airis passed upwardly through the lower grate. The fuel usually reachesthis grate in a partially-consumed state and quite finely subdivided. Itis desirable that it accumulate on the lower grate and become coked andbe slowly consumed. This process is promoted by providing a series ofpockets within which it may accumulate, and I obtain such pockets by thestaggered arrangement of the bars," most of the fuel finding its waybetween the bars 11 and resting directly upon the bars h. Again, it isimportant that the surface of the lower grate be well covered with fuelin order that whatever draft there may be through it shall be uniformlydistributed. Unless direct feeding upon the lower grate is resorted tothe quantity of fuel reaching the same is comparatively small, and thearrangement of grate-bars shown results in concentrating it by arrangingit in rows between the bars H. A still further advantage arising fromthe staggered arrangement of the bars of the lower grate is found in thefact that by this arrangement the passages between the bars may be madequite small, so as to prevent the dropping therethrough of the fueluntil it has been thoroughly consumed, but are twice as numerous as whena single set of bars is used, and hence ample provision is made fordraft through the grate when it is desired to complete the combustion ofthe fuel by opening the ash-pit door. Such openings may be provided inthe face of the furnace as may be desired for feeding and draft. I showa door g, giving access to the chamber above the upper grate, a door g,giving access to the chamber between the two grates, and a door 9 givingaccess to the ash-pit. As the grates extend continuously from side wallto side wall of the furnace, there will usually be employed two doorsfor each of these chambers.

Two flue-openings are provided in the wall a, leading from the chamberbetween the upper and lower grates, and arches 7.: 7c" are builtimmediately back of the walla, one inclosing each of its fine-apertures,these arches being continued backwardly a considerable distance andhaving their rearward ends closed, as shown at 70 The arches 7:; 7c arespaced a small distance apart, and near the bottoms of their adjacentwalls they are provided with apertures k alternate bricks being omitted.The interspace K between the two arches 7c 70 forms a combustion-chamberor retort. There may be sprung across the rearward end of this chamberor retort an arch 7c ,which serves, together with the arches 70 k, tosupport the header d. The precise location of this header isimmaterial-thatis to say, the tubes E may have any preferred length. Theadvantage of locating the header a little forward of the rearward endsof the arches 70 7c 70 is found inthe fact that the plugs closing theapertures opposite the ends of the tubes E are thereby protected fromthe intense heat of the flame by the masonry.

The operation of the furnace is as follows: Fires are started andmaintained on both grates. Then the fire is well established,

firing upon the lower grate may be discontinued, the fuel therefor beingsupplied from the upper grate to better advantage, it being undesirableto. develop smoke from below in large quantities. The direction of thecurrents is downwardly and backwardly and upwardly and backwardly,respectively, moving in lines which intersect as they enter themixing-chambers inclosed by the arches Is. As the vapors enter thesechambers longitudinally and leave them through theirlateral apertures,they are caused to swirl or roll and become thoroughly intermixed. Thewalls of these chambers soon become highly heated, and combustion iscontinued and increased as the vapors enter and pass through them. Asthe two currents of burning gases emerge from the apertures 70 into theretort-flue K they clash, and the most intense heat is-developed at thispoint. The thorough intermixture of the gases and the high temperatureattained result in complete combustion. It will be seen that thismaximum of temperature is developed directly below the rearward ends ofthe water-tubes E. The highlyheated vapors for the most part ascendamong these tubes to the crowu-sheet of the boiler, following it back toits rear end. Such of the vapors as pass out of the retort-flue Kbeneath the arch k also rise to the crown-sheet.

By the construction described all the ad vantages of a combineddowndraft and updraft furnace are secured and the vapors are thoroughlyintermingled and burned before they come into contact with thecomparatively cool surface of the boiler and are directed thereagainstwhen they have attained their greatest temperature.

The combination of the mixing-chambers with the central-retortcombustion-flue are not dependent for their successful operation uponthe arrangement or kind of grates employed, though the relation of allthe parts as shown and described I regard as the most advantageous, thecommodious chamber between the upper and lower grates and theinclination of the upper grate contributing to the freedom of draft andthe highest efficiency of the mixing-chambers.

The arrangement of the pipe system has positive advantages. Both egressand ingress tubes communicating with the boiler through its end theconnections are more easily and cheaply made than when through the sidewalls. The water is drawn from the boiler a little above its lowestpoint, so that the sediment is not drawn into the pipe system. All

of the tubes and headersare readily'accessible for cleaning Withoutdisconnecting any of them, and, as already explained, the contractionand expansion of any one or more of the tubular grate-bars does notdisturb the remainder of the system or any part of it.

I claim as my invention.

1. In a furnace, the combination with a firebox, a wall, a, closing therearward end of the fire-box and having two flue-apertures, a down?draft-grate composed of water-tubes forming parts of a circulatingsystem, such tubes pass ing through the wall a above its apertures andbeing prolonged backwardly, and an updraft-grate below such apertures,of arches inclosing such apertures and extending backwardly and beingclosed at their rearward ends, said arches being spaced apart-and having flue-apertures at the bases of their adjacent walls.

2. In a furnace, the combination with a fire= box, a Wall, a, closingthe rearward end of the fire-box and having two flue apertures,adowndraft-grate composed of water-tubes forming parts of a circulatingsystem, such tubes being inclined upwardly from their front ends andpassing through the wall a above its ap ertures and being prolongedbackwardly in a horizontal plane, and an updraft-grate below suchapertures, of arches inclosing such apertures and extending backwardlyand be ing closed at their rearward ends, said arches being spaced apartand having flue-apertures at the bases of their adjacent walls.

3. In a furnace, the combination with'a fire box, a Wall, a, closing therearward end of the fire-box and having two flue-apertures,adowndraft-grate composed of water-tubes forming parts of a circulatingsystem, such tubes passing through the wall a above its apertures andbeing prolonged backwardly and entering a header, d, and anupdraft-grate below such apertures, of arches inclosing such aperturesand extending backwardly and being closed at their rearward ends, saidarches being spaced apart and having flue-apertures at the bases oftheir adjacent walls,the header, d, being supported upon the arches.

4. In a downdraft-furnace, the combination with a fire-box and a wall,a, closing the rearward end thereof and having a flue-opening, of aseries of water-tube grate-bars ex tending from the front of thefire-box through the wall a above the fiue, such tubes being inclinedupwardly in the fire-box and bent downwardly back thereof, andwater-headers for receiving both ends of the tubes.

5. In a downdraft-furnace, the combination with a fire-box and a wall,a, closing the rearward end thereof and having a flue-opening, of aseries of water-tube grate-bars extending from the front of the fire-boxthrough the wall a above the flue, such tubes being inclined upwardly inthe fire-box and bent downwardly back thereof, the wall, a, beingapertured to allow the tubes to bow upwardly as they expand.

OREL D. ORVIS.

Witnesses:

E. G. WATRoUs, LOUIS K. GILLsON.

